A Comprehensive Review on Low-Temperature Combustion Technologies for Emission Reduction in Diesel Engines

Diesel engines are lean burn engines; hence CO and HC emissions in the exhaust are less likely to occur in substantial amounts. The emissions of serious concern in compression ignition engines are particulate matter and nitrogen oxides because of elevated temperature conditions of combustion. Hence the researchers have strived continuously to lower down the temperature of combustion in order to bring down the emissions from CI engines. This has been tried through premixed charge compression ignition, homogeneous charge compression ignition (HCCI), gasoline compression ignition and reactivity controlled compression ignition (RCCI). In this study, an attempt has been made to critically review the literature on low-temperature combustion conditions using various conventional and alternative fuels. The problems and challenges augmented with the strategies have also been described. Water-in-diesel emulsion technology has been discussed in detail. Most of the authors agree over the positive outcomes of water-diesel emulsion for both performance and emissions simultaneously.

Development of a wall jet model dedicated to 1D combustion modelling for CI engines

Diesel engines are becoming smaller as technology advances, which means that the fuel spray (or jet) interacts with the cylinder walls before combustion starts. Most fuel injection 1D models (especially for diesel fuel) do not consider this interaction. Therefore, a wall-jet sub-model was created on an Eulerian 1D diesel spray model. It was calibrated using data from the literature and validated with experimental data from a fuel spray impacting a plate in a constant volume combustion chamber. Results show that the spray moving along the wall has a higher mixing rate but less penetration as an equivalent free jet, therefore they show a similar volume. Spray-wall interaction creates a stagnation zone right before the impact with the wall, and friction of the jet with the wall is relatively low. All these phenomena are well captured by the wall-jet sub-model.

Solid Selective Catalytic Reduction: A Promising Approach towards Reduction of NOx Emission from Exhaust of CI Engines

The rising rate of pollution in urban areas has become a worldwide concern in recent years. Diesel engines are considered one of the largest contributors to environmental pollution caused by exhaust emissions, and they are responsible for several health problems as well. Diesel engines contain carbon monoxide, carbon dioxide, unburned hydrocarbons, and oxides of nitrogen. The reduction of Nitric oxides (NOx) emission from diesel engine exhaust is currently being researched by automotive manufacturers. After much research, selective catalytic reduction (SCR) technology was discovered to be effective in reducing nitrogen oxide emission from diesel engine exhaust. This paper is an attempt to explore the problems associated with the use of selective catalytic reduction (SCR) and compares selective catalytic reduction (SCR) with the latest technology named solid selective catalytic reduction (SSCR) for efficient reduction of NOx emission from the exhaust of diesel engines. The issue of contamination, malfunctioning, and freezing of diesel exhaust fluid (DEF) at low temperatures are the major problems associated with the application of SCR. It is observed that by controlling the quantity of ammonia slip, SSCR can give better performance in the reduction of NOx emission from the exhaust of diesel engines.

Characterisation and Assessment of Physicochemical Properties of Grapeseed Methyl Ester Using Predictive Correlations and ASTM Standards For CI Engine Application

In the present work, a detailed investigation of the physio-chemical characteristics of grapeseed methyl ester (GSME) obtained from winery biomass waste has been carried out to evaluate its suitability as an energy alternate, for CI engines. GSME was subjected to Gas chromatography and mass spectrometry analysis from which fatty acids compositions were determined followed by other interpretations such as carbon number, number of double bonds, etc. Two different predictive correlations were identified from the literature for predicting the properties that are considered important, for using GSME as a fuel. The predicted properties of GSME are compared with the experimental results obtained through standard ASTM procedures, for diesel, neat grapeseed oil (GSO) and GSME, respectively. Further, the influence of the structural and compositional characteristics of GSME on the physicochemical properties like density, kinematic viscosity, lower calorific value, etc. has been evaluated and found to be closer to diesel.

Performance and emission characteristics of diesel engine using ether additives: A review

Pressure on alternative fuels and strict environmental regulations are driving a strategic shift in the efficient use of renewable biofuels. One of the promising biofuel candidates recently interested by scholars is a biological or organic additive that is added into diesel or biodiesel fuel to improve engine performance and reduce pollutant emissions. With efforts to improve efficiency and combustion quality in cylinders, combustion characteristics, flame structure and emission formation mechanism in compression ignition (CI) engines using blended fuel with organic additives have been studied on the effect of additive properties on the combustion behaviour. In this review, the physicochemical properties of typical organic additives such as ethers compounds and their effects on engine performance and emission characteristics have been discussed and evaluated based on conclusions of recent relevant literature. The results of the analysis revealed the prospect of using ether additives to improve combustion in cylinders and reduce pollutant emissions from CI engines. Obviously, the presence of higher oxygen content, lower viscosity and density, and higher cetane number resulted in a positive change in the combustion dynamics as well as a chain of mechanisms for the formation of pollutant precursors in the cylinder. Therefore, ether additives have a significant contribution to the sustainable energy strategy of the transportation sector in the next period when internal combustion engines still dominate in the competition for energy system choices equipped on vehicles.

Performance and emission characteristics of dual fuel engine using biodiesels

The introduction of the strict emissions norms is diverting the research for the development of new technologies which leads to the reduction of engine exhaust emissions. The usage of biodiesel in CI engine can enhance air quality index and protects the environment. Biodiesel can do an increment in the life of CI engines because it is clean-burning and a stable fuel when compared to diesel. Moreover, biogas has the potential to decrease both nitrogen oxides and smoke emissions simultaneously. Operating the engine in dual-fuel mode can provide lower emissions and a proper substitute for diesel. In this research, a modified CI Engine with single cylinder is used. Biogas is used as primary fuel and diesel, Mahua oil-diesel blend and Fish oil-diesel blend are used as secondary fuel. The effect of various secondary fuel blends on performance and emission characteristics in dual fuel engine are compared. In light of the performance and emission qualities it is reasoned that, utilization of the dual fuel mode in engine signifies the durability and lessens the harmful emissions from the engine with the exception of hydrocarbon and CO emissions. The excessive viscosity of fish oil and mahua oil prompts inconvenience in siphoning and spray attributes. The incompetent mixing of raw fish oil and raw mahua oil with diesel and biogas including air leads to incomplete combustion.

Research on the Control Mode of Homogeneous Charge Compression Ignition Combustion Working Process and Its Technical Prospect

The homogeneous charge compression ignition (HCCI) engine is considered an advanced technique, a form of internal combustion in which well-mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition. HCCI engines have higher thermal efficiency and lower emissions than Spark Ignition (SI) and Compression Ignition (CI) engines. The emissions of NOx can be neglected compared to the CI engine. In addition, a wide variety of fuels, combinations of fuels and alternative fuels can be used in this type of internal combustion engine. Moreover, when investigating the heat release rate of a HCCI engine for both single- and two-stage ignition fuels, the results show that for both fuel types, the cycle changes in the ignition and combustion phases increase with the delay of the combustion phase. Also, the cycle change of iso-octane (the single-stage ignition fuel) is higher than that of PRF80 (the two-stage ignition fuel). This paper will first introduce the control mode of the HCCI engine and then review its current status from the perspective of combustion, emissions, and consumption. After presenting the current status, the authors present suggestions about the prospect of further development with respect to the timing of ignition, the expansion of the engine operating range, and the choice of fuel mixture in this new mode of technology.